Generation of large sound waves in an outlet space of a compressor is known. From various reasons, it is useful to enable damping of these sound waves.
A sound deadening device having such a sound wave damping function is disclosed in, for example, JP 02-124214 U.
The sound deadening device of JP 02-124214 U includes an introducing pipe, a discharge pipe, and an expansion chamber that is communicated with the introducing pipe and the discharge pipe. In this sound deadening device, rapid change in impedance is generated by cross-section change of the introducing pipe, the expansion chamber, and the discharge pipe, and a sound wave is reflected on the boundaries, so that a sound deadening effect is exerted.
However, in the sound deadening device of JP 02-124214 U, resonance is generated on a facing surface in the direction in which fluid is discharged from the expansion chamber. Accordingly, sound pressure near an outlet becomes high, and the sound deadening effect is lowered.